Firearm aiming sights may use a thermal imaging camera to capture a thermal (infrared) image of a target scene and display the image in visible light on a display viewed by the user in order to enhance night-time and other low light vision or to detect warm objects through foliage, camouflage, fog, dust, or other obscurants. Alternatively, such aiming sights may use an image intensifier or other high sensitivity camera or imaging system to amplify low levels of visible light from the target scene or image other spectral bands of light not detectable by the human eye and display the resulting images to the operator via a phosphor screen or other type of display. In either case, it may be advantageous to superimpose the image from the camera or the intensifier on a direct view image of the target scene.